Many digital camera manufacturers list resolution in effective megapixels. This is based on a standard generally accepted in the industry and gives a reasonable indication of the maximum number of pixels the camera uses to create an image.
Some manufacturers use the total number of pixels on the camera's sensor, which includes many that aren't included in the final image. We state effective megapixels in all our specifications.
The greater the resolution, the more storage space you'll need.
• SDHC: Secure Digital High Capacity cards have a larger capacity (up to 32GB) but look exactly the same as the earlier SD cards.
• CF II: Compact Flash is the largest of the storage card formats, although it is still only 43mm x 36mm and 3mm thick. It is a popular format for DSLR cameras due to its larger capacity, high speed and durability. However, SDHC cards are becoming more popular these days.
• xD: xD Card is a format used primarily in Olympus and Fuji digital cameras.
• MS Duo: small-format version of Memory Stick from Sony. The MS PRO Duo is the same format with larger memory capacities and faster transfer speeds.
Digital cameras are usually power hungry and, as a general rule, rechargeable batteries are a good idea. However, some cameras are more energy efficient than others. Also, in some situations (such as travelling), being able to use normal alkaline batteries is a real advantage. Fortunately some can, but most can't, so having a spare rechargeable is important. This information is available in the comparison table.
A connection port that allows you to look at your pictures or movies on a TV. This is a handy way to show your pictures to a group and allows your digital camera to function as a highly portable display device. HDMI connections are even better because they combine best quality sound and video via cable.
In the details window of the compare SLRs tool the number refers to how long it takes from when the shutter button is pressed until the shutter opens to take the picture.
We do four tests; one with a target at one metre and the second with the target at 10 metres from the camera. This way we can tell which cameras have a noticeable delay when the auto focus is engaged. This is repeated with the camera in Liveview mode.
We can measure down to thousands of a second, but anything less than one tenth of a second is probably as fast as you'll need.
Although this may not always be possible, try to have the prefocus engaged and focused on the scene beforehand and be ready for the action to unfold. This will give you a better chance of taking that perfect shot as the shutter delay on even the slowest camera would be reduced considerably.
Can delete an image immediately after taking
In the details window of the compare SLRs tool a 'Yes' indicates that it is possible to delete the most recently taken picture before it is saved to the camera's storage card, that is, while it is still only in the camera's temporary memory. This can be particularly important if you are storing pictures in RAW format, as they may take some time to write to the storage card.
This is a measure of how long it takes from when the camera is switched on until the first picture is taken. In our test, the camera is first set to flash suppressed, full automatic operation, monitor enabled, zoom at its widest, with a distant landscape as a target. Then the camera is switched OFF. The test time starts when we press the POWER button. The shutter button is depressed either immediately after switching the camera on, or (because some cameras inhibit shooting while starting up) as soon as the camera is ready.
The test is repeated at least five times and these times are then averaged to give us the time shown.
Light comes in many colours - fluorescent is usually greenish, tungsten (normal household bulbs) is red/orange and daylight blue to red depending on the time of day. Automatic white balance should make sure whites always appear white regardless of the lighting conditions, but sometimes you'll get a better result if you can manually override the automatic setting.
With longer lenses it can be difficult to hold the camera still, which can lead to slightly blurry pictures. Image stabilisation can help by adjusting internally for the camera movement. This is the best system and is often referred to as "optical anti-shake" where the lens elements move. Some cameras now have a mechanical system where the camera's sensor moves.
Some use a system called Best Shot Selection (BSS) where the camera will automatically take a number of images when you press the shutter and decide for itself which of them has the least blurring. Generally BSS is considered to be a compromise solution.
Some manufacturers are also including electronic systems with titles such as Anti Shake DSP, Advanced Image Stabilisation or just Anti Shake. These almost always operate by increasing camera sensitivity (that is, amplifying the CCD signal), using shorter shutter times for the exposure and post-processing the image data. Often there's a clearly visible reduction of picture quality, with image sharpness reduced and picture noise increased.
We test using a device that moves the camera in both horizontal and vertical planes to approximate the amount of movement an average person would have if they held the camera unsupported. (This has been determined by measuring the amount of shake from a number of people using acceleration sensors applied to their hands.) The camera is set to its maximum optical zoom and photographs are taken with varying amounts of shake with the image stabilisation both on and off. The resulting images are checked to see what difference there is between those with and without image stabilisation. We look for reduction in distortion from shake, sharpness and any increase in picture noise. The focal length of the lens and increases in ISO are also taken into account.
Ultimately, if you're taking pictures in a low light situation or with a long lens, you'd be better off using a tripod.
A way for digital cameras and inkjet printers to communicate. The printer and camera don't have to be of the same brand, but the connection between them must be via a USB cable. Once connected, the camera can control the basic printer functions so you can print without the need for a computer. Most newer cameras have it and all do in this test.